1. Field of the Invention
The present invention relates to a twin-shaft concentric motor, and specifically to a novel improvement for miniaturization and space saving by coaxially aligning a pair of motors to reduce the shaft length.
2. Description of the Related Art
As the type of a conventional twin-shaft motor, a motor structure shown in FIG. 1 is disclosed in WO94/23911 according to PCT Application, for example.
That is, as shown in FIG. 1, in a case 1, first and second motors 2 and 3 are arranged to be laid up in the axial direction. A first rotor 4 of the first motor 2 and a second rotor 5 of the second motor 3 are respectively connected to first and second members 6 and 7 disposed in the upper part.
Therefore, the members 6 and 7 can be independently operated by independent rotation of each of the motors 2 and 3.
Since the conventional twin-shaft motor is structured as above, the following problem has been involved.
That is, since the motors are arranged in series to be laid up in the axial direction, the longitudinal length increases so that miniaturizing cannot be achieved by reducing the shaft length.
Accordingly, it is an object of the present invention to solve the above-mentioned problem, and in particular to provide a twin-shaft concentric motor for achieving miniaturization and space saving by coaxially aligning a pair of motors to reduce the shaft length.
A twin-shaft concentric motor according to the present invention comprises first and second stators arranged concentrically to each other; and first and second rotors formed between the first and second stators and being rotatable independently of each other. The twin-shaft concentric motor may further comprise first and second stator partition walls and first and second rotor partition walls for maintaining a vacuum side and an atmospheric side separated, respectively, so that the stators are located under atmospheric pressure while the rotors are located under vacuum pressure. Also, in the twin-shaft concentric motor, a permanent magnet may be provided on each surface of the rotors. Furthermore, the twin-shaft concentric motor may further comprise first and second detecting means for independently detecting the rotational angle of each of the rotors, wherein the first and second detecting means may be formed of code plates disposed in each of the rotors and sensors respectively opposing each of the code plates, and wherein the code plates and the sensors may form magnetic encoders. Preferably, the code plates are made of a ferromagnetic material and have anticorrosive coating formed on the surfaces thereof, and a hollow portion is formed in the axial center of a case supporting the stators.